High-Port Vs. Low-Port

[Psychobob_007]

what is the difference between the high-port and the low-port intake manifold on the SR20DE motor. is there a difference in performance? are they a dirrect replacement of each other or are there different parts for each? thanks.

[stinkyturbo]

no difference in performance & they are not direct replacements. different stud patterns.

[Q45tech]

Changed to conform to 1994 emission standards [not quite as perky as older version].Less aggressive cam timing, etc, etc.

Always EPA legal to install a later version but going earlier can create problems.

[supreamS14]

http://autospeed.com/cms/A_110298/article.htmlThe straight intake ports were designed with what Nissan terms an ‘aerodynamic port shape’, that is, a port that decreases in cross-sectional area as the runner/intake port gets closer to the intake valve. The ports were also positioned high in the head, so reducing the angle which the air had to negotiate before entering the combustion chamber. In addition to improving flow, the greater length of the port served to improve torque through giving a longer tuned length to the intake port/intake runner combination. In fact, a combined intake port/runner length of 450mm was used in the SR20DE engine. Compared with a low port design, the high port design improved measured torque by 4 – 7 ft-lb at engine speeds of over 4400 rpm.

Sorry for the old thread post!